One example of an application for the apparatus of the present invention is highwall mining. During the past forty years, highwall mining has proven to be an efficient method of mining coal, or other sought after material, that would not be mined by other methods. Highwall mining is a form of mining frequently used to supplement strip mining.
Strip mining is used when the sought after material deposits, such as coal, occur relatively close to the surface. In strip mining, the top several layers of earth over a coal deposit are removed to gain access to the coal deposit. The material of the covering layers is called overburden. When the coal to overburden ratio falls below a certain ratio, the process becomes unprofitable and strip mining ceases to be the economically preferred technique at that location. At that point in time, the strip mining has produced a large pit with seams of coal extending from the surface of the walls of the pit back into the earth. Highwall mining is a type of mining used to extract, or mine, the coal in the seams terminating at the walls of the pit.
In highwall mining, a highwall mining machine is located on the pit floor in alignment with a coal seam and a remote operated cutter module is forced into the coal seam. The cutter cuts a series of parallel rectangular cuts back into the seam up to 1,000 feet from the face of the wall. This is considered too dangerous for the insertion of any personnel and the cutter modules are directed and operated remotely. The coal mined by the cutter module is transported from the cutter module to the surface area by augers or conveyor belt systems.
Typically, the cuts and the entries to the cuts are rectangular. The width of the entry to a cut is dependent on the type of cutter module used, and the width may vary from 9-½ feet to 12 feet. The height of the entry is more dependent on the coal seam's thickness, and the height may vary from 28 inches to more than 15 ft.
As the high-wall miner progresses back into the mountain, a specialized form of conveyor is built behind it. This conveyor is comprised of multiple sections of push-beams. These push-beams are low profile and hollow on their interior. Within their hollow interior is at least one auger, but most typically, there are two augers. The first push-beam behind the high-wall miner receives coal, or other mined material from the high-wall miner and the augers within this first push-beam pulls the material back towards the push-beam behind it. Each push-beam receives the mined material from the one preceding it in the mine and the augers within it pull the material onward out of the mine until the material is conveyed fully out of the mine to a station at the floor of the mine pit. The augers are usually driven by the station at the exit of the mine shaft. As the mining machine recedes further underground, additional push-beams are added and pushed back in along with the machine.
This is a highly automated process and no personnel are allowed back into the high-wall mine shaft. The high-wall miner and the push-beam augers are operated and powered from the station external to the high-wall mine shaft. On occasion, the high-wall miner may become lodged in the high-wall mine shaft or some problem may arise with the push-beam conveyor back in the high-wall mine shaft. When this occurs, personnel are not allowed in to troubleshoot or inspect the source of the problem. Therefore, operators are left to blindly manipulate the high-wall miner to attempt to free it. This is frequently not successful. This can result in a highly expensive piece of capital equipment being irretrievably lodged within the high-wall mine shaft. There is a need for an apparatus which can travel back into the high-wall mine shaft and provide a visual of the situation as well as having the capabilities to perform certain functions to free the high-wall miner from its lodged position. Alternatively, the apparatus could disconnect the high-wall miner from the push-beam conveyor system, as the push-beam conveyor is itself a highly expensive piece of equipment. Each section of push-beam conveyor that can be retrieved would by itself provide a considerable savings even if the high-wall miner itself were lost.
At present time, it is estimated that there are more than one hundred highwall miners being operated in the coal industry, each one producing multiple cuts during an operating day. They all have the same problems to varying degrees. A need exists for a system capable of recovering, or assisting, lodged high wall mining machines and associated conveyors. Substantial monetary gains may be achieved by recovering the lodged components. In some cases, the seam being mined may be more fully exploited when the miner is freed or otherwise serviced.
Additionally, once a disabled miner, and or conveyor, is recovered and the cut cleared, a highwall miner can return to the cut to further exploit the seams at that location for further monetary benefit. For monetary purposes, the system must be efficient, reliable, and not labor intensive. For safety purposes, the system must not require personnel to be exposed at or near the highwall of the pit. The system should be able to work in close proximity with high wall miners.